Usually associated with the Lutherans, a good number of Reformed people also embrace the Law-Gospel hermeneutic or at least some variation of it. Immediately equating every imperative with 'Law' and therefore something apart from Gospel, this hermeneutic leads its adherents to a number of strange interpretations as well as generating scores of 'problem passages'.
There is of course a legitimate Law-Gospel distinction. It's Redemptive-Historical and notes the thematic Christocentric development and unfolding of salvation throughout the course of history. Thus it necessarily must make a distinction between the New Covenant era and the covenants which preceded it. There's overlap and interplay, continuity and contrast. But this scheme understands 'law' in terms of an epoch of history, a typological covenant form now fulfilled and obsolete. And even if it grants there was a works principle present in the old order that isn't there today, it by no means requires that all commands are necessarily separated from the Gospel, or that the Gospel itself cannot necessitate imperatives, obligations and expectations.
Wrong turns can lead to serious misreadings and misapplications of Scripture.
The Lutheran Law-Gospel distinction represents just such a misapplication and it really comes through when I hear someone from this camp discussing the Great Commission of Matthew 28. Because there's a command to disciple and mention of observance (obey, keep, hold fast) this cannot (it is argued) refer to Evangelism. That would be an introduction of imperative or command into the notion of the Gospel.
What then does it refer to? According to this reading it refers to those who have been evangelised and are now through this mandate encouraged to 'discipleship'. This label of discipleship and the notions such as obedience that accompany it are treated as not part of Justification but tied in with Sanctification. The Commission therefore is not about seeking out new believers (making disciples). Disciples it is argued are Justified persons pursuing a greater understanding and intimate knowledge of their declared righteousness. The Gospel under this scheme is merely Justification. It takes precedent and dominates the system. All other aspects of salvation and soteriology are read in light of this Law-Gospel paradigm of Justification.
Even under this reading the nearly ubiquitous notion of obedience in the New Testament is still problematic. Since they posit we cannot possibly be obedient (in any sense) then it is really just something of a hypothetical exhortation that's meant to drive us once more to the cross. 'Law' is never meant to be taken as a true command but as something that points to what we cannot do and thus drive us to grace.
While that's certainly a hermeneutic that magnifies grace, is this the grace or even the Gospel presented to us in Scripture?
While indeed all of our works are flawed and recognition of that drives us repeatedly to Christ, this hermeneutic is actually an addition to Scripture and distorts the full-scope of the Gospel. Disciples are Christians, there's no distinction. It was all the more surprising that the one who was arguing otherwise regarding The Great Commission was not a Semi-Pelagian proponent of Carnal Christianity but a convinced if not somewhat rationalistic Calvinist. Actually it is rationalism itself that is the problem here.
There's not a separate commission for Sanctification. Sanctification is not something supplemental but is clearly testified in the New Testament as but one component or facet of the whole soteriological picture. It is an integral part of salvation and Christians/Disciples bear fruit, depart iniquity, put to death the old man, endure and manifest obedience. It is the outworking of regeneration. In the days before Scholasticism returned and came to dominate Protestant thought the Reformers could speak with such freedom and use regeneration and sanctification as virtually synonymous terms. Not a few readers are both baffled and troubled by this as they read Calvin for the first time.
All of these works and fruits are imperfect and flawed but they demonstrate something essential... vitality, a life, a walk in the Spirit and as James makes abundantly clear, they are necessary. Faith without works is dead.
The Law-Gospel hermeneutic cannot seem to grasp this and is forced to resort to gymnastics when it comes to many texts. The Scriptures don't speak the way they speak much in the same way they don't fit the language and categories of Systematic theology. Though Biblicism is decried by these camps it must be contended they are guilty of conceptualizing some type of Centraldogma which they now utilize as an arbiter of revelation. Anything, any text or pericope which rationally violates the Centraldogma must be re-cast in a different light.
For the Law-Gospel hermeneutic it is the doctrine of Sola Fide that takes center stage. While the doctrine of Justification by 'Faith Alone' is true, even the Sola aspect of it, to utilize it as a lens through which to view and shape all of Scripture is a terrible mistake. If there is a key to Scripture, a Central doctrine by which we understand the whole it is without a doubt Christocentric. The advocates of what must be called Hyper-Solafideism would argue that is in fact what they are doing.
But it's not. While Christ is certainly essential to their scheme, it is the grace-works paradigm which dominates their system. Admittedly it's rooted in Christ's person and work but the paradigm doesn't do full justice nor accurately reflect the full scope and orb of New Testament teaching. Like the Five Points, the Law-Gospel Hermeneutic falls into the trap of reductionism. Rather than reflecting Scripture and allowing it speak even if it transcends our ability to systematize it, they elevate Sola Fide to the position of axiom and deduce a system which is in fact a synthesis of the Centraldogma (or axiomatic conglomeration) and sacred revelation. While they claim to be adherents of Sola Scriptura, the Magisterial Reformation and Post-Reformation notion of this is deficient and we must look elsewhere to find a more faithful testimony and application of the principle.
The New Testament knows nothing of a Christian who is not a disciple and knows nothing of a faith that does not produce obedience. Regardless of the imperfections, flaws, and corruption with regard to our motivations, the obedience we exhibit is a testimony to our Union with Christ and the transformative and renewing work of the Holy Spirit which brings us into conformity with Christ. We are called to walk in light of His Kingdom and to partake in His sufferings. Any Gospel which exempts this has cheapened the nature of the message, its demands and the power of the Holy Spirit to bring these elements into effect.
The Law-Gospel hermeneutic whether it means to or not ends up functionally treating Sanctification as something that is both optional and hypothetical. Church history bears this out. The separation has led numerous groups down speculative and ultimately destructive paths seeking to find some expression of the 'next step' in the move toward discipleship. Increasingly they turned to more subjective and experiential notions of how this would come to pass. It's not surprising because objectively in terms of Scripture there wasn't really any support of such a notion in the first place.
We can agree with the critics of Pietism that the 'normal means of grace' are sufficient but when applied in a Constantinian or Cultural Christianity context the 'normal' means are corrupted and degraded. When they are separated from a faithful and vigorously preached word that makes demands of its hearers the 'normal' sacraments are reduced to empty forms.
When you have a doctrine that can't be preached vigorously and imperatively demand antithesis for fear of confusing law and gospel than you have no ability to disciple, no ability to stir obedience and no means of letting the word function as a sword. In another piece I will argue this way of understanding 'Faith Alone' also effectively destroys Church Discipline.
The Word will cut. It either cuts hearts and effects change or it will cut out the chaff as it were. It will burn off the dross. The Word provokes a response. People will change or they will get offended and leave.
It is an unfaithful application of Scripture that produces stagnation and it is an impotent gospel that preaches grace with no demands. Grace is cheapened and so is the enduring salt and light of Christian witness. We're not speaking of preserving culture, but maintaining witness in the face of culture. A gospel that doesn't demand or produce antithesis quickly become indistinguishable from the world. The Theonomists have grossly abused the antinomian label but in this case it is applicable at least in a generalized sense.
It would seem that even MG Kline struggles with this somewhat as he recognizes the Matthew 28 passage as echoing the covenantal language previously seen in the Mosaic order. However he (properly) wishes to emphasize the very different nature of the Gospel epoch. Salvation has always been by Grace through Faith in the person and work of Christ but there was another typological layer to the Old Covenant order, a works principle reminiscent of the Garden. Israel as a type of Adam entered the Garden in the form of Canaan, the land of milk and honey, a repeat of the primaeval paradise. To maintain this status there was a requirement of obedience. For Adam this was as an individual, for Israel (as typological Adam and thus typological Christ) it was corporate, comprehended on a national level.
Kline would argue the 'works principle' was something that only existed under the Old Covenant order and was only applicable on the corporate level in terms of Israel's ability to stay within the land.
The Church Age is the Already-Not Yet manifestation of the Consummate Kingdom. It is the heavenly reality present by the Spirit in the fallen world. The Kingdom-Ecclesiastical order cannot be abrogated or superseded. At this point we agree with Kline and thus there is no works principle in the sense of treating the entire order as probationary. In This Age we will know no other or subsequent covenant arrangement. The Covenant of this era is not typological. It's not comprised of unfulfilled symbolism.
Nevertheless the covenantal language in Matthew 28 does indeed echo the Covenant declarations which are also found in Moses and this in no way detracts from the graciousness of the Gospel. It didn't under Moses either and that's even if we allow for a corporate-level works principle.
The New Covenant Gospel worked anachronistically under the old order and the concept of obedience and mandated observation also functioned even prior to Moses in the person of Abraham. Faith without works is dead. The works are not meritorious. We do not merit Christ's merits. But the works are evidence of the living trusting faith at work in our hearts. There is no faith without them. Matthew 28 reiterates this aspect in the language of observance and obedience and though the New Covenant order cannot be superseded, individuals must indeed persevere, endure and throughout the New Testament the language associated with salvation is often cast in provisional terms.
Salvation is often qualified with an 'if' and there are constant warnings regarding the danger of falling away. The Law-Gospel Hermeneutic renders these many passages impotent and hypothetical. They are annoyances to the system.
Thus it must be understood that while the Ecclesiastical order cannot be replaced, individuals and individual congregations, microcosms of the order are also treated provisionally. They may fail, fall into apostasy and be removed even if the order as a whole cannot. We see this for example in the opening chapters of Revelation where individual congregations are threatened with the removal of their candlestick. Klineans would agree the candlestick represents the presence of the Holy Spirit necessary to ratify their status as localized manifestations of the heavenly council or gathering. Without a generalized obedience and adherence, which probably ought to be understood qualitatively rather than in some form of quantification, they are in danger of dissolution. By qualitative obedience we are suggesting that it is probably difficult to establish a set list of 'marks' or criteria by which this status can easily be determined. There are other considerations such a momentum and trajectory and this is also true with individuals.
As far as congregations go, Paul allows for provisional status in Titus. This has nothing to do with bureaucratic labels so common in denominational systems but with their formal status as viable congregations. Though they are not yet duly constituted they are progressing toward that mark and must both as a community and as individuals manifest the fruits of repentance and belief in order to maintain that status.
The Great Commission is a command for Christians to go out into the world, into the nations, and through the Word preached and through baptism 'make' Christians. Christians are taught to follow the Lamb and calling it obedience in no way detracts from the gracious character of the Gospel.